Answer:
A. 60°
Step-by-step explanation:
From the diagram, in triangle ABC,
AB=BC=CA=15 units.
This means triangle ABC is an equilateral triangle.
All angles in equilateral triangle are congruent. The sum of all interior angles in triangle is always 180°, so one angle of equilateral triangle is equal to 60°. Thus,
∠A=∠B=∠C=60°
